Bug 2547131 (CVE-2026-105243) - CVE-2026-105243 log4net-windows: log4net: Event log suppression via oversized messages in EventLogAppender
Summary: CVE-2026-105243 log4net-windows: log4net: Event log suppression via oversized...
Keywords:
Status: NEW
Alias: CVE-2026-105243
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-10-06 20:02 UTC by OSIDB Bzimport
Modified: 2026-10-07 10:39 UTC (History)
0 users

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:

Attachments (Terms of Use)

Description OSIDB Bzimport 2026-10-06 20:02:16 UTC 
Insufficient Logging vulnerability in the EventLogAppender of Apache log4net.

Long messages were truncated to a fixed size that exceeds what the Windows Event Log accepts once the log and source names are counted, and the event log then stored nothing and reported nothing. A party whose data reaches a log message could suppress the whole record by making it long enough. Only applications on Windows that use EventLogAppender are affected.

This issue affects Apache log4net: from 1.2.9 before 3.5.0.

Users are recommended to upgrade to version 3.5.0, which fixes the issue.
Note You need to log in before you can comment on or make changes to this bug.